Conventionally, a configuration for use as an image reading mechanism in a copier, a facsimile machine, a scanner or a multifunction peripheral is known in which a movable carriage is provided below a document platen (contact glass). With such an image reading mechanism, an image of a document placed on the document platen with the side to be read facing down on the document platen can be read by moving the carriage.
A document reading light source that applies light to the document is mounted to the carriage. In an image reading mechanism that uses a contact optical system, an image sensor for reading a document image (e.g., a complementary metal oxide semiconductor (CMOS) image sensor) is also mounted to the carriage. Power, a synchronization signal and the like need to be transmitted to the carriage, and thus the carriage is connected to the main apparatus, which is a supply source of the power, the synchronization signal and the like, with a flexible flat cable.
Meanwhile, with the recent wide spread use of electronic devices, there is an increasing demand for image forming apparatuses such as multifunction peripherals to have electromagnetic non-interference, or in other words, image forming apparatuses are required to not cause electromagnetic interference (EMI) that impedes the operations of other devices by emission of electromagnetic waves such as radiation noise during operation of the image forming apparatuses. The flexible flat cable mentioned above has a structure in which conductors having a rectangular cross section that are arranged in parallel are disposed between upper and lower plastic films, and the plastic films are heat-sealed. For this reason, the flexible flat cable easily emits electromagnetic waves and easily receives incident electromagnetic waves. To address this problem, various techniques have been proposed (see, for example, PTLs 1 and 2).
For example, a configuration that prevents a reduction in the amount of current caused by mutual inductance (electromagnetic coupling) between a plurality of flexible flat cables by inserting a metal film between the flexible flat cables is known as a first related technique (e.g., PTL 1, etc.). Note that the metal film is grounded.
Another configuration is also known as a second related technique (e.g., PTL 2, etc.) in which a plurality of flat cables are overlapped, at least part of the cable wires of each flat cable are alternately allocated to a signal wire and a ground wire, and at least part of the cable wires between adjacent flat cables are disposed such that a signal wire and a ground wire face each other.